Acute Pain & OFA pt3 Flashcards
What drug is fentanyl structurally similar to?
Meperidine
Fentanyl has ____ potency, ____ onset of action and _____ duration of action.
High potency
Rapid onset
Short duration
What is the priniciple metabolite of fentanyl?
Norfentanyl
Detectable in urine up to 72 hours after single dose.
Why is elimination of fentanyl slightly prolonged despite very short duration of action?
Lungs serve as large inactive reservoir (up to 75% of initial dose undergoes first pass pulmonary uptake).
Why is fentanyl more potent and rapid than morphine?
Greater lipid solubility
What is responsible for fentanyl’s short duration of action?
Rapid redistribution to fat and muscle
What is the protein binding of fentanyl?
84%
What is hydromorphone and how is it formed?
Hydrogenated ketone of morphine formed by N-demethylation of hydrocodone
Hydromorphone is ______ times as potent as morphine when administered orally.
3 - 5 times
Hydromorphone is ______ times as potent as morphine when administered parenterally.
8.5 times
What is hydromorphone’s primary metabolite?
Hydromorphone-3-glucuronide
What should be known about Hydromorphone-3-glucuronide?
- Lacks analgesic effects
- May potentiate neurotoxic effects (allodynia, myoclonus, seizures).
When is Hydromorphone-3-glucuronide’s neurotoxic side effects a significant concern?
Patients with renal insufficiency
What is the typical dose of parenteral Hydromorphone?
0.2 - 2 mg
What is the typical oral dose of hydromorphone?
2 - 8 mg
What is the duration of action of hydromorphone?
3 - 4 hours
What is hydrocodone derived from?
Codeine
How does the potency of hydrocodone and codeine compare?
Hydrocodone is 6 - 8 x more potent than codeine
What are the two most abused opioids?
1st = Oxycodone
2ⁿᵈ = Hydrocodone
What are the two metabolites of hydrocodone metabolism?
- Hydromorphone (via CYP2D6)
- Norhydrocodone (inactive) via CYP3A4
What is the morphine equivalent of hydrocodone?
1 mg morphine = 3 mg hydrocodone
What is typical hydrocodone dosing?
2.5 - 10mg w/ 300 - 750mg acetaminophen q4-6hours
consider max dose of acetaminophen
What receptors does buprenorphine have affinity to? (3)
μ - partial agonist (strong)
κ - antagonist (strong)
δ - agonist (weak)
What benefits does buprenorphine provide? (4)
- ↓ respiratory depression
- ↓ immune suppression
- ↓ constipation
- No accumulation in renal patients
What is the primary metabolite of buprenorphine?
Norbuprenorphine by CYPs
What should be known about norbuprenorphine?
- 1/50th analgesic activity of buprenorphine
- ↑↑↑ Respiratory depression
What is the IV/IM buprenorphine dose equivalence for morphine?
0.3mg IM buprenorphine = 10mg morphine
What is the half life of buprenorphine?
Long
20 - 73 hours
Should buprenorphine be avoided in patients with renal impairment?
No. Hepatic elimination primarily
What are the side effects and drug interactions of buprenorphine?
What opioid receptors do NSAIDs bind to?
Trick question. NSAIDs inhibition COX as their method of pain modulation.
What is the recommended dose for celecoxib?
100mg daily
What is the recommended dose for diclofenac?
50 mg BID
How might antidepressants work as pain medication adjuvants?
Modulation of spinal cord transmission to reduce pain signaling
Whats the IV dose of fentanyl for pain?
20 - 50 mcg
What anticonvulsants are used as adjuvant medication to relieve pain? (4)
- Gabapentin (watch for sedation/ respiratory depression in older patients)
- Phenytoin (dilantin)
- Carbamazepine (tegretol)
- Topiramate (topamax)
What skeletal muscle relaxants are used as adjuvant medication to relieve pain? (5)
- Baclofen (Lioresal®)
- Carisoprodol (Soma®)
- Cyclobenzaprine (Flexeril®)
- Methocarbamol (Robaxin®)
- Tizanidine (Zanaflex®)
What is Opioid Free Anesthesia?
- Technique where no intra-operative systemic, neuraxial, or intracavitary opioid is administered during the anesthetic.
Opioids acting on the Mu receptor will produce these unwanted effects. (5)
- Respiratory depression
- Decrease GI motility/ constipation
- Urinary retention
- Prurititis
- Physical dependence
Opioids acting on the Kappa receptor will produce these unwanted effects.
- Respiratory depression
- Dysphoria
Opioids acting on the Delta receptor will produce these unwanted effects. (4)
- Respiratory depression
- Urinary retention
- Prurititis
- Physical dependence
What is opioid-induced hyperalgesia (OIH)?
- State of nociceptive sensitization caused by exposure to opioids.
- The condition is characterized by a paradoxical response whereby a patient receiving opioids for the treatment of pain might actually become more sensitive to certain painful stimuli.
What are the recommended starting doses for tylenol and ibuprofen? Max doses?
- Tylenol: 500-1000 mg q6h Max 4g/day
- Ibuprofen: 200mg TID Max 3200mg/day
In general, the PO dose of opioids is about ___ the IV/IM dose.
PO dose is ~3x the IV/IM dose
